John h



(No ModeL) J. H. SHAW. GYLINDER LOCK.

No. 446,176. Patented Feb. 10,1891.

Miran STATES ATENT FFICE.

JOHN H. SHAIV, OF NEIV HAVEN, CONNECTICUT, ASSIGNOR TO THE SAR- GENT & COMPANY, OF SAME PLACE.

CYLINDER-LOCK.

SPECIFICATION forming part of Letters Patent No. 446,176, dated February 10, 1891.

Application filed December 8, 1890. Serial No. 373,911. (No model.)

To all whom it may concern: the invention consists in formingalongitudi- Be it known that I, JOHN H. SHAW, of New nal recess in the cylinder upon the side of Haven, in the county of New Haven and State the key-hole where the projection is to be apof Connecticut, have invented new Improveplied, the said recess being undercut, and then 5, ments in Cylinder- Locks; and I do hereby introducing into said recess a piece of metal declare the following, when taken in con in shape corresponding to the said undercut nection with accompanying drawings and the recess, but of a size to give the required proletters of reference marked thereon, to be a jection into the key-hole and as more fully full, clear, and exact description of the same, hereinafter described. i0 and which said drawings constitute part of A represents the cylinder, which is of the this specification, and represent, in usual external form. I.

Figure 1, a perspective view of the cylin- In the best method of preparing the cylinder after the guard-recesses are formed, but der to embody my invention holes a, b, more before the key-holeis out; Fig. Zaperspective or less in number, are bored longitudinally T5 view of the same after the key-hole is out; into the front end of the cylinder before the Fig. 3, a perspective view of one of the guards key-hole is cut and at points corresponding detached; Fig. 4 aperspective view of the cylto the position required for the projections inder with the guards introduced; Fig. 5, a orguards of the cylinder, and they are in such longitudinal central section of the cylinder position with relation to the key-hole that 20 through the key-hole, showing one of the when the key-hole B is cut, asseen in Fig. 2, guards; Fig. 6, opposite side views of the key; it will cut away less than one-half of the said Fig. 7, a transverse section through the cylinholes a b, as seen in Fig. 2, leaving longitudider cutting through the guards, showing the nal recesses at the sides of the key-hole of key in place; Figs. 8, 9, l0, and 11, modificasomewhat more than half a circle in trans- 25 tions. verse section.

This invention relates to an improvement From hard steel or other suitable wire of a in that class of cylinder-locks in which the diameter corresponding to the diameter of cylinder is adapted to receive a thin flat key, the holes a Z; pieces d are cut, as seen in Fig. and particularly to that class in which the 3, and these pieces are driven into the reo key-hole is provided with inward projections cesses a b of the sides of the key-hole, as seen or guards, so as to require that correspondin Fig. 4, and because the metal of the cylining grooves be made in the sides of the key, der embraces more than one-half the cylinthe invention relating particularly to the fordrical pieces thus introduced, those pieces mation of such inward projectionsin the keyare firmly held in their places and project 3 5 hole. These projections or guards are usuinto the key-hole, so as to form guards upon ally formed as an integral part of the cylinthe sides of the key-hole, as seen in Figs. 4 derthat is, of the same metal as the cylinand 5, there being two guards, one upon each der, and this metal is of a soft nature, so as side, as shown in Fig. 4. The key requires to to easily wear away or beremoved by evilbe correspondingly constructed, as seen in 0 40 disposed persons, it being understood that Fig. G. On one side the key is constructed these projections into the key-hole aid very with a longitudinal groove e, which corremuch in protection against tampering with sponds to the guard on one side, and with a the lock. Again, the formation of the keygroove fcorresponding to the guard of the hole with the inward projections as an inteother side, and so that when the key is intro- 5 5 gral part of the cylinder adds materially to duoed, as seen in Fig. 7, these grooves will the cost of manufacture. pass onto the respective guards, as shown in The object of my invention is a constructhat figure. In the case of a key of serpention which will permit such projections to be tine shape in transverse section, as seen in introduced after the key-hole is formed, and Fig. 8, the guards will be introduced accord- :1oo 50 so that they maybe made from a metal much ingly and as seen in that figure. In some harder than the metal of the cylinder; and cases a single guard on one side only is all that is required, but as many guards maybe introduced as desirable.

\Vhile I prefer to make the guards from Wire or pieces of cylindrical shape, so that holes may be bored into the cylinder before the key-hole is cut, the guards may be made of other shapeas, for illustration, dovetail shape, as seen in Fig. 9. Then after the keyhole is cut, as seen in Fig. 10, longitudinal undercut grooves are cut in the sides of the keyhole, as represented in Fig. 11. In this case the guards have the advantage of being made from hard metal, and the undercut grooves serve to hold them firmly in place, and it permits the same formation of the keyhole by a simple out, as in the first illustration. I therefore, while preferring the cylindrical shape of the guards and the corresponding undercut or cylindrical-shaped grooves or seats in the cylinder for the guards, do not wish to be understood as limiting the invention to the particular shape of the guards. By this construction the key-hole may be cut through the cylinder as if it were a plain flat key-hole, and the guards thus made independent of the cylinder may be made from a hard metal, so as to avoid the wearing away which necessarily follows Where the guards are made as an integral part of the softer-metal cylinder. 7

1. In a cylinder-lock in which the cylinder is constructed with a longitudinally fiat keyhole, the key-hole constructed with one or more longitudinal undercut grooves upon its said recesses being somewhat more than half a circle in transverse section, combined with guards of corresponding but of substantially full cylindrical shape set into said recesses in the said cylinder, substantially as described.

In testimony whereof I have signed this specification in the presence of two subscribe ing witnesses.

J OIIN H. SIIAXV.

\Vitnesses:

AUKER S. LYHUE, EGBERT H. EGGLESTON. 

